Apparatus to avoid bending during forging



Feb. 18, 1969 .1. M.THOMAS 3,427,853

APPARATUS TO AVOID BENDING DURING FORGING Filed Dec. 6, 1965 Sheet of 2 PRIOR ART /3 PRIOR ART 7 3 2 5 F/GZ.

Iuuawrog J2me M. Flo/was Aw-wways Feb. 18, 1969 .1. M. THOMAS 3,427,353

APPARATUS TO AVOID BENDING DURING FORGING Filed Dec. 6, 1965 Sheet g or 2 INVEMTOR Jack M- 771M145 United States Patent O 6 Claims ABSTRACT OF THE DISCLOSURE A manipulator and press assembly which maintains a workpiece presented to the press in a horizontal attitude and absorbs vertical shocks imparted to the workpiece during a pressing operation. A hydraulic cylinder and piston assembly is connected to the workpiece supporting means. Fluid is selectively admitted to the cylinder by a control valve from a pressure supply line in order to raise the supporting means whereby the workpiece may be presented to the open tools. Prior to the pressing step, fluid is exhausted from the cylinder by the control valve through a pressure relief line. The pressure relief line is adjusted to provide sufficient back pressure to balance only the weight of the supporting means whereby the workpiece lowers under its own weight until it rests upon the lower tool. As the press compresses the workpiece, additional fluid is exhausted through the relief line to absorb vertical shock and maintain the workpiece horizontal.

This invention is concerned with improvements in and relating to forging and it is an object of this invention to provide a new and improved forge and manipulator with a view to reducing the likelihood of bending a workpiece in the process of varying its cross-section between the tools of the press.

In the accompanying drawings FIGURES 1 and 2 are diagrammatic views of a workpiece held by a manipulator and being worked by the tools of a press.

In FIGURES 1 and 2 the workpiece which may be an ingot is shown at 1, the manipulator at 2, the lower fixed press tool at 3 and the upper movable tool at 4. Assuming that the peel and the unforged part of the ingot are held in a straight line by the jaws =5 and that the supporting structure of the peel is sufliciently rigid not to give, then when the ingot is being squeezed between the two tools of the conventional press, bending is induced if th ingot is incorrectly presented to the tool gap. It can be shown in practice, as illustrated, that, if the stock is too high the resultant forged shape is bent in an upwards direction and conversely, if too low, a downwards bent ingot is produced. 7

According to this invention there is provided a manipulat-or comprising a peel supported for movement in a horizontal attitude in a vertical plane whereby to permit, during a press cycle, a workpiece to move from an upper position or pass line in which the workpiece on axial movement will clear the tools when open, to a lower position in which the workpiece is in a horizontal attitude at the completion of the press tool approach movement and back to the upper position, means being provided to control the position of the peel in the vertical plane to locate the workpiece in the upper position when the tools are open and to permit the workpiece to maintain a horizontal attitude while under the action of the tools.

The fluid or hydraulic circuit preferably includes in a relief valve to permit the ingot weight to move the ingot down toward the lower tool from the pass level and to permit the forging load to lower the ingot by the amount of lower tool penetration. Furthermore the hydraulic circuit is preferably responsive to the motion of the movable press tool.

In order that the present invention may be well understood there will now be described one embodiment, given by way of example only, reference being had to the other figures of the accompanying drawing,

FIGURES 3, 4 and 5 being diagrammatic views of a press, manipulator and workpiece, and.

FIGURE 6 being a layout of the hydraulic circuit.

With reference to FIGURE 3, the centre line of the ingot has been positioned under the control of the normal parallel hoist 9 and the hoist cylinder 10, at a position above the bottom tool 3 which is suflicient to allow free longitudinal movement of the manipulator 2 without the ingot hitting the bottom tool. Under these conditions, a small pilot cylinder 11 is pressurised from the main oil supply line.

At the commencement of forging the press is instructed to begin its forging cycle and the top tool 4 begins to move downwards. At the same time, the small pilot cylinder is connected to exhaust through a variable relief valve 12 (FIGURE 6) and the peel and ingot 1 sinks until the ingot rests on the bottom tool, where further downward movement is stopped. The top tool continues to fall and the instant of contact is shown in FIGURE 4. Squeezing now begins and continues until such time as the required penetration is reached (FIGURE 5). During the time of squeezing part of the forging load has been transmitted through the ingot to the pilot cylinder and pressurising the oil, caused it to flow through the relief valve to exhaust. The rate of oil flow is such that the ingot and peel are maintained in a straight horizontal line.

After squeezing is completed the press cross-head is reversed and the top 'tool moves clear of the ingot. The sig nal to reverse the tool movement also actuates the control valve of the pilot cylinder which is now connected to the main oil supply line. Oil flows into the pilot cylinder which is returned to its starting position thus raising the ingot to the clear position and allowing free longitudinal motion.

FIGURE 6 shows the hydraulic supply circuit. This comprises a high pressure line 14, a non-return valve '15, an accumulator 16, a control valve 17 and the relief valve 12. The pressure relief valve is adjusted so that sufiicient back pressure is generated to balance the weight of the peel assembly alone. Any additional weight such as an ingot is suflicient to cause the complete assembly to sink until such time as the weight of the ingot is supported by the bottom tool.

The control valve is solenoid operated, the solenoid being responsive to the press control signal initiating downward motion of the upper press tool to couple the pilot cylinder to the relief valve and to the press control signal initiating reversal of the upper tool at the end of a working stroke. It will of course be understood that if desired the pressurising of the pilot cylinder and its coupling to exhaust could be initiated just before or after the reversals of motion of the upper tool at the ends of its stroke.

I claim:

1. A manipulator and press assembly comprising:

a press having upper and lower tools;

a peel;

means for mounting the peel for movement at all times in a horizontal attitude in a vertical plane whereby to permit, during a press cycle, a workpiece to move from an upper position in which the workpiece will clear the tools when open to a lower position in which the workpiece is in a horizontal attitude at the completion of the press tool approach movement and back to the upper position;

means for positioning the peel to automatically locate the workpiece in the upper position when the tools are open; and

means for controlling automatically the positioning means to permit the workpiece to sink from the upper position onto the lower press tool before the upper press t-ool engages the workpiece and to permit the workpiece to sink further under the action of the press tools whereby to permit to maintain the horizontal attitude of the workpiece.

2. An assembly according to claim 1 in which the positioning means comprise a piston and cylinder assembly and means for selectively coupling the cylinder to a line for feeding fluid under pressure to the cylinder.

3. An assembly according to claim 2 in which the controlling means includes a line for relieving pressure in the cylinder and a. pressure relief valve which is set so that when the relief line is selected, fluid in the cylinder will open the relief valve only if the peel is supporting a workpiece.

4. An assembly according to claim 3 in Which the line for fluid under pressure includes a non-return valve and an accumulator.

5. An assembly according to claim 2 in which the peel is supported by a main strut movable by the piston and cylinder assembly to move the peel, the strut being of adjustable length to permit the pass line height to be selected for a constant extension of the piston and cylinder assembly.

'6. An assembly according to claim 1 in which the peel is suspended on parallel links.

References Cited UNITED STATES PATENTS 2,221,539 11/1940 Gehret 7 2.--420 X 2,257,546 9/ 1941 Dienenthal et al 78-96 2,3 14,686 3/ 1943 Brosius 78-96 2,720,800 10/ 1955 Taylor 7'242.0 3,126,770 3/ 19 64 Wupperman et al. 7Q42 0 3,109,616 4/ 1964 Bell 72-420 CHARLES W. LANHAM, Primary Examiner.

E. SUTTON, Assistant Examiner. 

